The Obama Administration’s decision to prioritize the pursuit of a diplomatic solution to the Syrian government’s use of chemical weapons plunged Congress into a holding pattern Tuesday, complicating an already chaotic situation on Capitol Hill.

“There are so many moving parts,” says Congressman Aaron Schock, a Republican from Illinois. “The Administration’s statements continue to change over a 24-hour period. We’re going to strike, we’d like Congress’s approval, we don’t need Congress’s approval—that’s what we heard last week—to now we may not strike if Assad gives up his weapons to Russia.”

President Obama’s aides have indicated that even as they continue to seek Congressional authorization to use military force, they will now pursue international discussions on a Russian proposal to secure Syria’s chemical stockpile. An Obama administration official said those efforts “will begin today at the United Nations, and will include a discussion on elements of a potential U.N. Security Council resolution.” The official said the administration would seek signs of progress within days, or press ahead with Congressional votes.

The latest hairpin turn left some lawmakers hopeful that the U.S. could avoid becoming embroiled in a bloody civil war with no good outcome. Others were bewildered by the development, as a military strike suddenly slipped to Plan B before the White House lobbying blitz had even begun to ramp up.

In the meantime, the Senate, which is scheduled to act first on the issue, has begun adjusting its timetable. Senate Majority Leader Harry Reid postponed on Monday a procedural motion that would have paved the way for an initial Senate test vote on the use of military force. A bipartisan group of Senate negotiators are reportedly working on a proposal that would call for a team of United Nations inspectors to sequester Syria’s chemical weapons within a specific time frame. Exactly how long is unknown.

A diplomatic solution negotiated under the auspices of the U.N. could be a face-saving solution for the White House. It would hand Obama a reprieve from making the unpopular decision to plunge the U.S. into a sectarian conflict with ripple effects across a restive region. And it would avert a Congressional standoff that Obama seems increasingly likely to lose. On Tuesday, Republican Senate Leader Mitch McConnell and Ohio Republican Rob Portman said they would vote against striking Syria, adding their votes to a ledger that looks grim for the White House.

As they left a standing-room only meeting in the bowels of the Capitol, House Democrats indicated there was broad support within their caucus for a diplomatic solution. But Democrats, who were being counted on to supply the bulk of the votes on a resolution to authorize punitive strikes against Assad, are not off the hook yet.

“This is an opportunity. And it should be taken and looked at seriously,” says Democratic Senator Dianne Feinstein, who chairs the chamber’s Intelligence Committee. House Democratic leaders noted that 173 current members of Congress had voted for a 2003 bill designed to stop Syria’s development of weapons of mass destruction—which suggests they may be asked to live up to their commitment. “They need to vet this out,” Representative Steve Israel, the chairman of the Democratic Congressional Campaign Committee, told reporters Tuesday morning at a breakfast hosted by the Christian Science Monitor. “If this is a credible diplomatic alternative, take it. If this is a subterfuge, stay away from it.”

Steny Hoyer, the House Democratic whip, emphasized the need to ensure that it was not a “rope-a-dope” situation designed to stall the U.S. from acting. The timetable for making that assessment was “days, not weeks,” Hoyer said. But others said that White House chief of staff Denis McDonough, who briefed members during the hour-long meeting, had not specified a timetable for determining whether Russia’s proposal was a genuine offer or a tactical ploy. And House Democratic Leader Nancy Pelosi noted that if diplomatic negotiations dragged and Obama “sees an opportunity,” he still had the authority to strike.

House Democrats also sought to frame the proposal that emerged overnight as a longstanding White House position. “They’re claiming it was their idea in the first place,” says Congressman Alan Grayson of Florida, who opposes intervention, as he left the Democratic caucus meeting.

Obama made that assertion Monday night in an interview with Fox News. “I did discuss this with President Putin. This is something that is not new,” he said, adding that the topic was first raised with Russian leaders at the G-20 summit in Los Cabos, Mexico, in June 2012. “It doesn’t solve the underlying Syrian conflict, but if we can solve this chemical weapons issue, which is a threat to us and the world, then it does potentially lay the groundwork for further discussions around how you can bring about a political settlement.”

Republicans, who have panned Obama’s handling of the crisis from the start, were skeptical of the latest moves. But even some of the GOP’s most hawkish members conceded the Russian proposal was worth running to ground. “I don’t see Assad wanting to turn over his chemical weapons. I would think we have to assume from the start that this is a delaying attack by Russia,” says Republican Congressman Peter King of New York.

“Get a U.N. Security Council vote within a week and get a specified time in there,” King says, making clear his support for a possible diplomatic solution. “Can’t go more than a few weeks—the whole thing.”